Recently, as the degree of integration in semiconductor devices increases a shallow trench isolation (referred to as ‘STI’ hereinafter) structure has been used as a device isolation structure so as to improve a device isolation characteristic of the semiconductor devices.
The STI structure is a technology that forms a trench having a predetermined depth on a semiconductor substrate, deposits an oxide layer into the trench by a chemical vapor deposition (CVD), and removes any unnecessary oxide layer by a chemical mechanical polishing (CMP) process, thereby forming a device isolation layer. Since the STI structure has a better isolation property and smaller occupied area in comparison with a local oxidation of silicon (LOCOS) structure, it has been widely employed for highly integrated semiconductor devices. In particular, the LOCOS structure involves selectively growing a thick oxide layer on a semiconductor substrate to form a device isolation layer.
Conventionally, a plasma oxide layer or an undoped silicate glass (USG) layer formed by atmospheric pressure chemical vapour deposition (APCVD) was used to fill an STI trench. However, as a pattern size of a device is reduced, a method for filling the trench with a high density plasma chemical vapour deposition (HDP-CVD) oxide layer has been proposed.
The process for manufacturing an STI gap fill oxide layer during a formation of an STI is generally performed by an APCVD. The WJ1000/1500 has been the APCVD equipment most often used. WJ equipment for performing the APCVD process carries out an STI gap fill process in a belt manner using four injectors.
Referring to FIG. 1, a void 200 can occur in the related art STI gap fill oxide layer due to a surface reaction dependence of the gap fill oxide layer with the STI liner oxide layer during an STI CMP and subsequent wet clean process. Moreover, an incomplete interface layer damages a center part of the STI gap fill oxide layer. Accordingly, during a formation of a gate of the semiconductor device, poly oxides remain at the damage part of the STI gap fill oxide layer to deteriorate the reliability of the semiconductor device.